The present invention relates to a color separating optical apparatus which is capable of reading color-separated picture signals using a single light-receiving means.
Conventional types of apparatus contemplated by the present invention include color copying machines, color scanners, etc. The optical system of these apparatus is basically composed of a light source for illuminating the object, an imaging lens unit for focusing reflected light from the object on a light-receiving means such as a CCD or a photoreceptor drum, and a plurality of color-separating filters having different wavelength selection characteristics, which are inserted into the optical path for detecting plural pieces of color information using a single light receiving means.
In this type of apparatus, the color information on the object is color-separated on the basis of the brightness of each of the three primary colors, which necessitates receiving the reflected light from the object several times, with an appropriate filter being selected. The pieces of color-separated information are superposed to produce an output color picture that reproduces the color information of the object.
A problem with the apparatus described above is that the overall spectral characteristics of the system which are determined by the characteristics of the light source and the spectral sensitivity of the light-receiving means are not flat, so that different energies are produced for different colors. This results in the failure to perform effective control of color reproduction since the density of the output color picture will vary from one color to another.